In recent years, television program data have been digitalized, and been broadcast through ground waves or satellites or distributed via the Internet or a CDN (Contents Delivery Network). The digitalized television program data does not deteriorate, and can be reproduced, making copyright protection be a key issue.
Therefore, various proposals have been made on copyright protection of content including television program data.
Digital television receivers tend to offer high-quality, high-definition images. A digital television receiver that is called a 4K television and is capable of displaying an image of 3,840×2,160 pixels has recently gained attention as a next-generation model of a digital television receiver that is called a Full HD (High Definition) television and is capable of displaying an image of 1,920×1,080 pixels. As opposed to the 4K television, the Full HD television is also referred to as a 2K television.
As a method of distributing television program data for the 4K televisions, what is conceived is a method of distributing television program data of Full HD televisions (first content) by using, for example, ground waves (first transmission path), and distributing difference data (second content) between television program data of 4K televisions and television program data of Full HD televisions via, for example, the Internet or CDN (second transmission path). According to the method, alongside the 4K televisions, the Full HD televisions continue to be used.
By the way, home appliances have recently been connected together through wireless communication, such as Wi-Fi or the like that is compliant with the IEEE802.11 standard, without using cables. Accordingly, as a situation where a 4K television is used, the situation can happen where a 4K television that is provided as a home server and is connected to an indoor antenna terminal and a communication line terminal receives television program data, and the data is viewed through another 4K television in a different room that is wirelessly connected (third transmission path) to the 4K television.
In the case of the above distribution method for television program data of 4K televisions, some kind of copyright protection is applied to television program data of Full HD televisions that is distributed by using, for example, ground waves, and to the difference data (between television program data of 4K televisions and television program data of Full HD televisions) that is distributed via, for example, the Internet or CDN. Copyright protection methods thereof may be the same or different.
To transmit an image between 4K televisions that are wirelessly connected, some kind of copyright protection needs to be applied. According to general technique, a 4K television that is provided as a home server receives two items of data to which some kind of copyright protection is applied and decodes the two items of data, and combines two images to generate a 4K-television image, and encodes the image again and applies some kind of copyright protection before transmitting the image to another 4K television. After the data is received, the processes need to be completed without delay.
However, the re-encoding may cause deterioration in quality, and the processes are inevitably delayed due to the decoding and the re-encoding.